By which two processes does glucose enter cells in the human body?

Active transport and diffusion.
Glucose is transported by active transport, against the concentration gradient, from the gut into intestinal epithelial cells. Whereas glucose is transported by facilitated diffusion into red blood cells.
In the gut the glucose level is high so if facilitated diffusion int the intestinal epithelial cells occurred it could be lethal so active transport is needed to bypass this concentration gradient. Where as red blood cells have a low glucose level so facilitated diffusion along a concentration gradient is suited in this situation.